In 1999, he played a gay man in UK series Queer as Folk, a show that didn’t shy away from sex and homophobia. Five years later he stepped into HBO’s The Wire as an ambitious Baltimore politician. The crime drama was hugely influential, ushering in the age of box-set viewing.

Then came Game of Thrones. Gillen’s Littlefinger — brothel owner and arch manipulator — is, four seasons in, one of the few originals alive and scheming.

It’s certainly been a great run for the 46-year-old. But magic touch? Don’t be silly.

“I can read a script to know whether it’s good, then I’ll do what I can to go after it,” he says.

“I’ve managed to nail a few of those along the way, but there are other things I would have liked to have gotten that I didn’t.

In between groundbreaking TV series, Gillen has worked steadily in theatre and in mostly indie film projects (with the odd scene in The Dark Knight Rises thrown in to impress his kids).

Sansa (Sophie Turner) and Littlefinger (Aidan Gillen) in a scene from season 4 of
Game of Thrones.Source:Supplied

“If I’m in a series that has that level of visibility, I’ll use that to generally go in the other direction and try to do a lot of small-scale stuff,” he says.

“It often is with friends or past collaborators. I am happy on a massive movie set, but I’m equally as happy on a tiny, no-budget set — feeding myself and cycling to work.”

One of the small films Gillen veered into is Calvary. The black comedy is the second in a trilogy from writer/director John Michael McDonagh and leading man Brendan Gleeson.

Their first film, 2011’s The Guard, is the biggest local movie in Irish box office history.

Gillen has known McDonagh for a long time: “I acted in John’s first short film 14 years ago,” he says.

Like every other actor in that short, Gillen was offered a part in The Guard, but couldn’t do it.

Gillen, right, couldn’t pass up he chance to work with Brendan Gleeson, left, in
Calvary.Source:Supplied

Still, McDonagh called again with Calvary: “John’s very loyal. Often people say, ‘Do the short and when the feature comes, you’ll get the call’. But it doesn’t always happen that way.”

Gillen also wasn’t about to knock back working with Gleeson a second time.

“Everyone wants to work with Brendan; I put myself in that group. It was really nice to work with him after standing on the sidelines watching for 20 years. It’s one of his best performances, to be sure.”

The film casts Gleeson as a small town priest who is told in confessional he will be killed next Sunday. Given a week to get his affairs in order, the Father bounces between the oddball residents in his town — one of whom will do him in.

Gillen’s role as Littlefinger in
Game of Thrones impacted the way he looked for
Calvary.Source:Supplied

Gillen plays a doctor with a blackly cynical streak.

“He’s miserable, surrounded by death and decay. He’s self-medicating as well,” says Gillen. “A bit of inspiration I took for the doctor: I saw a guy once, sitting in a bar, reading the deaths column of the paper and just giggling away to himself.”

If Gillen has one regret about Calvary, it’s his facial hair.

“I was in the middle of Game of Thrones so there was a look I couldn’t shed — I could have done without the Petyr Baelish moustache. The HBO people are very accommodating, but you’ve got to be on first call for them, which means having a bit of facial hair.”

Season five of Game of Thrones begins shooting later this month, taking Gillen from Dublin up to Northern Ireland.

He has read the books the series is based on, so has had a fair idea where Littlefinger is headed. But in season five, the show will storm past the books.

“It’s an adventure everyone is on — the audience, the cast. Not knowing where it’s going, that’s good,” he says. “People playing end games could work … but if you don’t know what the end game is, maybe you won’t play the obvious thing.”

Aidan Gillen’s character in
Calvary is “miserable, surrounded by death and decay”.Source:Supplied

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